The present invention relates to a field shredder with a friction base, with a housing, a rotatable blade drum provided in the housing and a blade attached to the. blade drum, which cooperates with the friction base to finely chop harvested material.
Such a field shredder is known from DE 33 16 241 C 2. The friction base comprises a plurality of beams with cutting edges offset in alignment with the circumference and extending vertically to the axis of the drum across the width of the friction base. In such a friction base, there exists the problem that the harvested material jams between the ribs, thus pegging the friction base in such a way that the beams no longer protrude over the effective surface and no friction output exists any more.
A further field shredder with a friction base is known from DE26 42 103. In this field shredder, the friction base comprises a plurality of indentations pushed into metal sheets from the outside to the inside, the steeply climbing partial u of which is aligned with its edge opposite to the orbiting direction of the blade drum, extending vertically to the axis of the drum. The indentations comprise a small distance to one another and are offset in rows. The blade on the blade drum is set at a certain angle to a counter-blade on the friction base. As the base must remain dosed, the cutting edge can, if at all, only protrude upwards by about 4 mm. This small height is very quickly pegged in operation.
Therefore, the object of the invention is to provide a field shredder with a friction base in which the friction base is not pegged.
This object is solved by a field shredder with a friction base 10, with a housing 6, a rotatable blade drum 7 provided in the housing 6 and a blade 8 attached to the blade drum 7, which cooperates with the friction base 10 to finely chop harvested material, characterized in that the friction base 10 comprises a plurality of protrusions 11 spaced apart axially and circumferentially, the blade 8 comprises a cutting edge 12, the protrusions comprise at least two side surfaces 13, 14 with edges forming an angle with each other and which are both not parallel to the cutting edge 12 of the blade 8, and a first and a second set of blades 8 are provided, each arranged on one half of the blade drum 7 offset against one another in the direction of rotation of the blade drum 7 and the cutting edges of which are inclined towards the rotary axis of the blade drum 7.
As the protrusions which interact with the blades are spaced in an axial direction and in the direction of the circumference, the chopped harvested mat erial can easily exit again between the protrusions, thus pegging less the friction base. As the protrusions comprise two side surfaces interacting with the cutting edge of the blade, the effectively of the chopping activity is increased. This makes it possible for the protrusions to be arranged at a greater distance from one another than if they only comprised one side surface which interacts with the blade. The greater distance of the protrusions improves the cleaning capability, with the result that the friction base tends to be pegged less.
Preferred embodiments of the invention include one or more of the following features: pro-trusions 11 comprising a rectangular cross-section; pro-trusions 11 comprising a square cross-section; protrusions 11 provided in a parallelepiped shape parallel to the rotary axis of the blade drum 7; protrusions 11 comprising a circular or an oval cross-section, with the longitudinal axis of the oval extending parallel to the rotary axis of the blade drum 7; and blades 8 inclined against the rotary axis of the blade drum 7 in such a way that they show a V shape in a top view.